Generally, a lighting device generates light therefrom and collects the generated light thereto to emit the light in one direction.
For example, the lighting device includes a fluorescent light, an incandescent light, a halogen light, a mercury light, a sodium light, a metal light or the like.
In addition thereto, recently, an LED (Light Emitting Diode) is used as a light source of the lighting device.
The LED is an optoelectronic device which has a bonding structure of p-type and n-type semiconductors to allow electrons and holes to be bonded to each other upon application of power to emit the light of energy corresponding to the band gap of the semiconductors therefrom.
Advantageously, the LED has relatively low power consumption, semi-permanent life span, low fatigue in optic nerves, and various colors, and accordingly, the LED has been recently used for indoor and outdoor lighting.
The brightness of the LED is proportional to the strength of electric current applied to the LED.
However, if the strength of electric current is increased to raise the brightness of the LED, the strength of heat generated from the LED is also increased to cause the LED to be damaged due to the heat, thereby undesirably shortening the life span of the LED.
So as to solve the above-mentioned problems, there is proposed Korean Patent No. 10-1142936 (dated on May 10, 2012) entitled “light emitting device”.
The conventional light emitting device includes a substrate having a heat pipe, an insulation film disposed on the substrate, electrode terminals located on the insulation film, and an LED package mounted on the electrode terminals, wherein the substrate having the heat pipe includes a body having at least one empty internal space, an operating fluid injected into the empty internal space, and a wick disposed on the inner peripheral wall of the empty internal space.
Under the conventional light emitting device as configured above, the LED package or a light emitting chip is mounted on the substrate having the heat pipe, and the heat generated from the LED package or the light emitting chip is radiated to the outside, thereby cooling the LED package or the light emitting chip.
However, the substrate having the heat pipe itself absorbs the heat generated from the LED package to cause the heat to be increased locally, thereby undesirably resulting in the malfunction of the LED package.
Besides, the substrate having the heat pipe has a shape of a simple container plate to cause the returning passage of the operating fluid to be extended further, so that the circulation of heat through the operating fluid is not gently achieved, thereby undesirably failing to efficiently radiate the heat.